## Waves

• WM10.1 Bell Laboratory's Wave Machine

This consists of rods connected in parallel by a stiff metal wire. When an impulse is given to one end, the wave travels the length of the strand and comes back. Holding the last rod in place will flip the returning wave. It is preferable to use the longest set because that gives the nicest waves.

• WM10.2 Rubber Rope

This is used to show the relationship of v=F/µ. As the rope is stretched, F increases and p. decreases. The can also be used to show the phase after reflection. Also, standing waves can be shown. A volunteer holds one end of the rope. Another one starts sending waves. The number of nodes n is n=21/w, where w is the wavelength, or n=21 v/v, where v is the frequency. Thus, we see that increasing the frequency or decreasing the tension in the rope increase the number of nodes n.

• WM10.3 Y-Rope

Send a wave down the main length of the rope. The wave splits into two waves at the junction and the amplitudes are smaller than the original. That is, amplitudes add.